Separating device for the bodywork of a vehicle

ABSTRACT

A separating arrangement for the self-supporting bodywork of a motor vehicle has a partition which is arranged at the front end of a rear compartment, extends in the transverse direction of the vehicle and over part of its height between rear wheel houses of the motor vehicle and is fastened to boundary walls of the rear compartment. The separating arrangement is designed as a supporting device which strengthens the bodywork against distortion. The separating arrangement is curved in relation to a vertical transverse plane of the vehicle and a horizontal transverse plane of the vehicle, and the separating arrangement has reinforcing struts in the form of greater material thickness along force flow lines.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to a separating arrangement.

The “bodywork stiffness” is increasingly regarded as one of the mostimportant criteria for modern motor vehicles. It makes a decisivecontribution to safety, high-quality appearance and comfort. However,the increase in the bodywork stiffness is often associated with anincrease in the vehicle weight, since a number of measures arefrequently associated with additional or stronger bodywork components.

German document DE 198 43 025 C1 describes the possibility of increasingthe bodywork stiffness while reducing the mass using a component used asstandard, a dividing wall of the fuel tank. The dividing wall is of flatconfiguration and is virtually parallel to a vertical transverse planeof the vehicle. Angled elements and rails, with which the separatingarrangement is fastened releasably to the bodywork, are in turn fastenedto the dividing wall. In addition, the separating arrangement hascross-shaped cross-struts which are fitted on the separating arrangementor are integrated as a U-profile in the component.

U.S. Pat. No. 5,195,780 describes an approximately box-shapedarrangement which surrounds the fuel tank and is connected to thebodywork, this arrangement likewise contributing to stiffening thebodywork.

German document DE 196 42 820 A1 discloses a rear end of a vehicle, inparticular for a convertible, which is configured in such a manner thatthe forces which are introduced via the chassis and via a crossmemberinto a central force flow center point are conducted further. The forcesare distributed from there into a plurality of supports which arearranged in a manner similar to a lattice-type structure. However, thearrangement is not optimized in respect of a reduction in weight.

An object of the invention is to design a separating arrangement of amotor vehicle rear compartment in such a manner that the bodyworkstiffness is increased in comparison with the prior art with asimultaneous reduction in mass.

The object is achieved according to the invention.

A novel separating arrangement according to the invention is fittedreleasably in the front part of a rear compartment of a motor vehicle.It serves inter alia to partition off a fuel tank compartment from therear compartment. The separating arrangement is positioned in such amanner that it is curved in relation to a vertical transverse plane ofthe vehicle (SFQ) and a horizontal transverse plane of the vehicle(WFQ). The separating arrangement is preferably curved concavely inrelation to these planes but, given an appropriate distribution of spacebetween the fuel tank compartment and rear compartment, a convexcurvature may also be expedient. The curvature increases the bodyworkstiffness in comparison with the prior art.

A further novel feature is that the separating arrangement has increasedmaterial thickness along the calculated force flow lines. Accordingly,material may be saved outside the force flow lines, this leading to areduction in weight while simultaneously increasing the stiffness. Theforce flow lines are calculated for the corresponding bodywork withreference to standard loading situations (e.g. torsion and bending ofthe bodywork) with the aid of the finite element method. According tothe invention, the force flow line profile is applied to the separatingarrangement.

In a further advantageous refinement, the separating arrangement has, atits edges, fastening surfaces which are formed approximately parallel tothe vertical or horizontal transverse planes of the vehicle. Thisresults in a greater compensation of tolerance in two directions inspace during the assembly of the body shell.

The use of elongated holes in the fastening planes additionally resultsin a compensation of tolerance in the third direction in space.

The separating arrangement is preferably fastened directly to thevehicle bodywork by screwing. Additional elements, such as angledcomponents and rails, may be omitted. The number of screws is reduced.This measure contributes to the reduction in weight.

A further reduction in weight can be effected by the separatingarrangement being produced in a light metal casting, in particulardiecasting. Diecasting is understood here to mean all types of castingin a permanent casing die at increased pressure, for example diecasting,squeeze casting, thixocasting, thixomolding, vario-casting orlow-pressure chill casting. Sandcasting processes or gravity chillcasting are possible, but are not always expedient because of cost.

The abovementioned casting processes make it possible to fashion theseparating arrangement according to the invention from light metals and,in particular, to vary the wall thicknesses in accordance with theinvention. This results in a lower component weight and in a higherbodywork stiffness. Suitable casting metals are aluminum alloy andmagnesium alloy and what is referred to as AZ91.

The reduction in weight is likewise assisted by designing the wallthicknesses between the reinforcing struts to be as thin as possible,i.e. as thin as permitted by current casting technology. At the saidlocations, the wall thickness is approximately 1.5 mm or less. At thepresent time, wall thicknesses of 1.2 mm can be reliably fashioned bycasting techniques.

It is particularly expedient with regard to the reduction in weight todesign the regions between the reinforcing struts to be free frommaterial. However, this requires an additional working step and possiblyan additional punching tool. The expediency of this measure iscalculated in an individual case by an analysis of thecost-effectiveness.

A releasable fastening of the separating arrangement permits maintenancework in a fuel tank compartment covered by the separating arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are illustrated in the followingfigures, in which:

FIG. 1 shows the rear end of a self-supporting bodywork with aseparating arrangement in a perspective view, and

FIG. 2 shows a perspective view of a separating arrangement.

DETAILED DESCRIPTION OF THE INVENTION

The detail illustrated in FIG. 1 of the self-supporting bodywork 2comprises a rear compartment 6 which is separated from a fuel tankcompartment (not illustrated specifically) by means of a separatingarrangement 4. The separating arrangement 4 extends from a base 7 of therear compartment 6 as far as a crossmember 9 and between two wheelhouses 8, of which only the right-hand one can be seen in theperspective illustration. The separating arrangement 4 has a curvaturein relation to a horizontal transverse plane of the vehicle WFQ and avertical transverse plane of the vehicle SFQ.

A detailed illustration of the separating arrangement 4 is provided byFIG. 2. The curvature of the separating plane is designed concavely inrelation to the WFQ and the SFQ, this bringing about an enlargement ofthe fuel tank compartment. The separating arrangement 4 has reinforcingstruts 10 which correspond to the force flow directions, which aredependent on the type of vehicle.

The reinforcing struts 10 concern reinforcements of the material incomparison with the rest of the wall thickness. The reinforcement of thematerial can be fashioned very readily in a casting process, sincelocally greater wall thicknesses can be reproduced by the form tool. Thereinforcing struts 10 have a cross section, the width to height ratio ofwhich is greater than 1; this ratio is preferably greater than 4. Thereinforcing struts 10 are therefore to be referred to as flat, thishaving an advantageous effect on their profile over the curvature. Highreinforcing struts would run the risk, when subjected to load, ofbuckling over the curvature.

Cutouts 16 which are worked mechanically from the separating arrangement4 after a production process by means of diecasting are situated betweenreinforcing struts 10. In this case, the cutouts 16 in FIGS. 1 and 2 arepurely exemplary. Only the reinforcing struts 10 are emphasized moreclearly by this illustration. According to the invention, the gapsbetween the reinforcing struts 10 may also consist of material of thinwall thickness, preferably of 1.5 mm or less.

For assembly purposes, the separating arrangement 4 has fasteningsurfaces 12 which run approximately parallel in relation to the WFQ andthe SFQ. These surfaces 12 which are “parallel to the network” permit acompensation of tolerance during the assembly in an x- and z-direction(see system of coordinates in FIG. 1). Elongated holes 14 which permitan additional compensation of tolerance in the y-direction areincorporated into the fastening surfaces 12.

The arrangement described of the fastening surfaces 12 and of theelongated holes 14 makes it possible to omit further auxiliary means forfastening the separating arrangement 4. The separating arrangement 4 isscrewed directly to the bodywork 2. A permanent connection betweenseparating arrangement 4 and bodywork 2 is conceivable but not expedientin most cases since the fuel tank compartment should be accessible.

The separating arrangement in FIG. 2 additionally has installationdevices 18 for the integration of electronic components. Theinstallation devices 18 are configured in the form of raised parts whichcan already be provided with holes during the casting process by meansof sliders. This measure enables additional auxiliary fastening meansand the provision of holes to be omitted, which saves additional workingsteps, material costs and weight. The installation devices areconfigured in such a manner that the desired positioning of theelectronic components is ensured.

1. A separating arrangement for the self-supporting bodywork of a motorvehicle, comprising a partition which is arranged at a front end of arear compartment, extends in a transverse direction of the vehicle andover part of its height between rear wheel houses of the motor vehicle,and is fastened to boundary walls of the rear compartment, wherein theseparating arrangement is designed as a supporting device whichstrengthens the bodywork against distortion, wherein the separatingarrangement is curved concavely in relation to a vertical transverseplane of the vehicle and a horizontal transverse plane of the vehicleand partitions off the rear compartment from a fuel tank compartment,and wherein the separating arrangement has reinforcing struts in theform of a greater material thickness along calculated force flow lines.2. The separating arrangement as claimed in claim 1, wherein theseparating arrangement has fastening surfaces which are parallel inrelation to the vertical transverse plane of the vehicle and in relationto the horizontal transverse plane of the vehicle.
 3. The separatingarrangement as claimed in claim 2, wherein the fastening surfaces areprovided with elongated holes.
 4. The separating arrangement as claimedin claim 1, wherein the separating arrangement is fastened directly tothe vehicle bodywork.
 5. The separating arrangement as claimed in claim1, wherein the separating arrangement is fashioned from a light metaldiecasting.
 6. The separating arrangement as claimed in claim 1, whereina wall thickness between the reinforcing struts is less than 1.5 mm. 7.The separating arrangement as claimed in claim 1, wherein regionsbetween the reinforcing struts are left open.
 8. The separatingarrangement as claimed in claim 1, wherein the separating arrangement isfastened releasably to the bodywork.
 9. The separating arrangement asclaimed in claim 5, wherein the separating arrangement is fashioned froma magnesium diecasting.
 10. The separating arrangement as claimed inclaim 2, wherein the separating arrangement is fastened directly to thevehicle bodywork.
 11. The separating arrangement as claimed in claim 3,wherein the separating arrangement is fastened directly to the vehiclebodywork.
 12. The separating arrangement as claimed in claim 2, whereinthe separating arrangement is fashioned from a light metal diecasting.13. The separating arrangement as claimed in claim 12, wherein theseparating arrangement is fashioned from a magnesium diecasting.
 14. Theseparating arrangement as claimed in claim 3, wherein the separatingarrangement is fashioned from a light metal diecasting.
 15. Theseparating arrangement as claimed in claim 14, wherein the separatingarrangement is fashioned from a magnesium diecasting.
 16. The separatingarrangement as claimed in claim 4, wherein the separating arrangement isfashioned from a light metal diecasting.
 17. The separating arrangementas claimed in claim 16, wherein the separating arrangement is fashionedfrom a magnesium diecasting.
 18. The separating arrangement as claimedin claim 2, wherein a wall thickness between the reinforcing struts isless than 1.5 mm.
 19. The separating arrangement as claimed in claim 3,wherein a wall thickness between the reinforcing struts is less than 1.5mm.
 20. The separating arrangement as claimed in claim 4, wherein a wallthickness between the reinforcing struts is less than 1.5 mm.
 21. Theseparating arrangement as claimed in claim 5, wherein a wall thicknessbetween the reinforcing struts is less than 1.5 mm.
 22. The separatingarrangement as claimed in claim 2, wherein regions between thereinforcing struts are left open.
 23. The separating arrangement asclaimed in claim 3, wherein regions between the reinforcing struts areleft open.
 24. The separating arrangement as claimed in claim 4, whereinregions between the reinforcing struts are left open.
 25. The separatingarrangement as claimed in claim 5, wherein regions between thereinforcing struts are left open.
 26. The separating arrangement asclaimed in claim 2, wherein the separating arrangement is fastenedreleasably to the bodywork.
 27. The separating arrangement as claimed inclaim 3, wherein the separating arrangement is fastened releasably tothe bodywork.
 28. The separating arrangement as claimed in claim 4,wherein the separating arrangement is fastened releasably to thebodywork.
 29. The separating arrangement as claimed in claim 5, whereinthe separating arrangement is fastened releasably to the bodywork. 30.The separating arrangement as claimed in claim 6, wherein the separatingarrangement is fastened releasably to the bodywork.
 31. The separatingarrangement as claimed in claim 7, wherein the separating arrangement isfastened releasably to the bodywork.